Anyone who has met Housing Authority chairwoman Rosanna Wong Yick-ming cannot help but be impressed by her sincerity, firm grasp of housing affairs and determination to overhaul the Housing Department. Nor can it be doubted that Director of Housing Tony Miller is one of the most able administrators in the civil service.

Even legislators making the push to pass a motion of no confidence in the two probably agree that they form a formidable team. But in trying to force them to stand down, the legislators have a bigger objective in mind. They are trying to set a precedent whereby senior officials take political responsibility for blunders within their ambit. The motion is yet another bid to push for the introduction of a ministerial system that has won cross-party support but is resisted by the administration.

Appearing before the Legislative Council yesterday, Chief Executive Tung Chee-hwa defended Ms Wong and Mr Miller, saying they should not be held responsible for problems that dated back many years and which they were trying to tackle. So many institutions and people were involved that it was unfair to lay the blame on them, he said.

Mr Tung's words showed that his stance on ministerial government has not changed. In January he told Legco that there was no consensus yet on the definition of a ministerial system. He said the current political system as provided for by the Basic Law maintained an "executive efficiency" that safeguarded prosperity and stability. But if Mr Tung had assessed the operation of the system, he would have come to the conclusion that it was clumsy and imposed great strains on both officials and politicians.

Hong Kong's executive-led political system is one in which elected politicians with a mandate wield no power; power is in the hands of unelected officials. Ambitious people keen to pursue a career in politics can only get elected as legislators, but do not get a chance to translate the wishes of their electorate into action. The most effective way of asserting themselves is to gainsay the administration.

It is a system that frustrates not just the politicians. Senior officials find that the long hours of hard work they put in to ensure things work smoothly are not rewarded, but any lapses invite harsh and fierce criticism from politicians and the media. They have to lobby support for what they consider to be evidently good policies from legislators who can always find fault, often for the sake of opposition.

Some officials have apparently left because they found the heat unbearable. For example, former secretary for treasury Kwong Ki-chi and former secretary for financial services Rafael Hui Si-yan, both high-fliers in the administration, are believed to have quit the civil service for more lucrative but less high-profile jobs because they did not want to bear the brunt of unfair slurs. Mr Kwong now heads Hong Kong Exchanges and Clearing and Mr Hui is the managing director of the Mandatory Provident Fund Schemes Authority. On the other hand, some of Hong Kong's most able politicians, including former Citizens Party chief Christine Loh Kung-wai and Liberal Party heavyweight Ronald Arculli, have also quit Legco after getting tired of the game of meaningless brinkmanship with officials.

Messrs Kwong, Hui, Loh and Arculli are all very talented and their departure from public life is a loss. Sadly, Ms Wong's public service career is also likely to come to an abrupt end. That too would be regretted. But it would be wrong to allow our affection for Ms Wong to override reason. Ms Wong has been chairwoman of the Housing Authority for seven years. Despite her best efforts, she has been unable to stop the latest scandals. If she accepts the buck stops with her, she should step down to set an example. As a career civil servant, Mr Miller cannot be dismissed; but he should be moved to another position as a sign of accountability.

The crux of the whole issue is that a system in which no senior official is ever held responsible for any blunders is clearly problematic. With further democratisation of Legco, tension between elected legislators and unelected officials will only intensify if the system remains unchanged.

Already, an increasing number of senior civil servants are said to be wary of becoming department heads and policy secretaries because they do not relish the prospect of crossing swords in public with what they consider to be gimmicky politicians. On the other hand, the system is also discouraging talents from standing for elections.

Unless a ministerial system is introduced so that the top jobs in the Government go to people who are ready and willing to take the heat, how can our civil servants be protected from political criticism and how can we encourage the talented to spend time and money to run for elections?